You can try set PHP_LSAPI_CHILDREN a little higher than "Max Conn", sometimes, a PHP children process could be not responding due to canceled requests or something. like "max conn = 40", "PHP_LSAPI_CHILDREN=50".

Ok, there wasn't the trailing M on the web console. It's strange that during the time the load was very high and many saw those 503 unavailable errors...there was over 2GB of free cached memory according to the graphs.

I don't think so, whenever the load is high, it always show those in the log. I noticed that the lines contain POST almost every time, seems like a member is trying to post to the forums. Why can't it just process them anyway (although slower) instead of giving those 408 timeout errors. Errors on the screen is not good for visitors to see. I rather have it run slower than having an error displayed.

I think I'm going to switch back to Apache soon, at least it doesn't show 503, 408 errors...still processes every request, just slower during high load periods. It's a shame I have to do this, lsws is a wonderful product but it has some flaws not present in Apache...